Polyether end-blocked with hydrolyzable silyl groups, method of manufacturing and room temperature curable composition thereof

ABSTRACT

A polyether having molecular weight from 1,000 to 50,000, end-blocked with hydrolyzable silyl groups and represented by the general formula (P): ##STR1## where R 1 , R 2 , R 6  and R 7  individually represent a divalent hydrocarbon group, R 4  represents a monovalent hydrocarbon group, R 8  represents an alkyl group with 1 to 6 carbon atoms, X represents an aromatic or heterocyclic ring, a represents a number from 1 to 3, m represents a number from 10 to 500, n represents a number of 1 or greater is produced and utilized in room temperature curing compositions containing inorganic filler and curing catalyst. There is also disclosed a method for producing the above polyether by reacting polyoxyalkylene end-blocked with epoxy groups, dimercapto compound and organo silicon compound.

BACKGROUND OF THE INVENTION

This invention concerns a polyether end-blocked with hydrolyzable silylgroups that can be cured at room temperature into a rubber-likeelastomer upon contact with moisture, and a method of manufacturing thesame. This invention also relates to a room temperature curingcomposition comprising such a polyether as an ingredient. The roomtemperature curing composition cures to a rubbery elastomer havingparticularly good heat and weather resistance, and having good adhesionbefore cure with no residual tackiness on the surface after cure.

The room temperature curing composition of this invention, comprisingthe above polyether, is suitable for use as a sealant. Similar prior artpolyethers as well as their use in sealants are well known as disclosedin Japanese Patent Publication Kokai No. 50-156599, etc. Sealants basedon such polyethers have been employed for the joints of buildings orjoining portions in transportation machines (Japanese Patent PublicationKokai No. 52-73998, etc.) However, since the prior art sealants of thistype are poor in heat resistance and weather resistance, they areundesirable for use in the joints of building outer walls requiringweather resistance, or in joints exposed to a relatively hightemperature, for example, certain joining portions in transportationmachines. Further, since the sealants of this type have no substantialadhesive property, it is required to apply the sealant after primertreatment of the surface to be bonded. Additionally, since the surfaceof cured sealant remains tacky, there is a problem that dust or the likeis liable to be stuck to the sealant.

This invention is for overcoming these problems and the object thereofis to provide a room temperature curing composition capable of curing toa rubbery elastomer having good heat and weather resistance, and havinggood adhesion before cure with no residual tackiness on the surfaceafter cure. This invention further provides a polyether endblocked withhydrolyzable silyl groups which is useful as a base polymer in sealants,as well as a process for producing such a polyether.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a specimen used for the shear resistancetest. All of the units for values in the drawing are expressed inmillimeters.

1 .. sample

2 .. adherend (glass, aluminum or polyvinyl chloride-coated steel plate)

DETAILED DESCRIPTION OF THE INVENTION

This invention concerns a polyether having a molecular weight from 1,000to 50,000 and end-blocked with hydrolyzable silyl groups represented bythe general formula (P): ##STR2## where R¹, R², R⁶ and R⁷ individuallyrepresent a divalent hydrocarbon group, R⁴ represents a monovalenthydrocarbon group, R⁸ represents an alkyl group with 1 to 6 carbonatoms, a represents a number from 1 to 3, m represents a number from 10to 500, n represents a number of 1 or greater and X represents anaromatic or heterocyclic ring.

This invention also relates to a process for producing a polyetherhaving a molecular weight from 1,000 to 50,000 and end-blocked withhydrolyzable silyl groups, by reacting:

(A) a polyoxyalkylene end-blocked with epoxy groups represented by thegeneral formula: ##STR3## where R¹ and R² individually represent adivalent hydrocarbon group and m represents a number from 10 to 500,

(B) a dimercapto compound represented by the general formula:

    HS--X--SH

where X represents an aromatic or heterocyclic ring, and

(C) an organo silicon compound having an epoxy group and hydrolyzablegroups represented by the general formula: ##STR4## where R⁴ representsa monovalent hydrocarbon group, R⁶ and R⁷ individually represent adivalent hydrocarbon group, R⁸ represents an alkyl group with 1 to 6carbon atoms and a represents a number from 1 to 3.

This invention further concerns a room temperature curable compositioncomprising: (I) 100 parts by weight of a polyether having molecularweight from 1,000 to 50,000 end-blocked with hydrolyzable silyl groupsand represented by the general formula (P), where P is as describedabove, (II) 3 to 300 parts by weight of inorganic filler and, (III)0.001 to 20 parts by weight of a curing catalyst.

In the polyether according to this invention represented by the generalformula (P), the oxyalkylene unit represented by R¹ O is preferably anoxyethylene unit, oxypropylene unit or a combined system of oxyethyleneunit and oxypropylene unit. Oxypropylene unit is particularly preferredsince the raw material is easily available, polymerization can beconducted easily and a liquid-state can be maintained readily even at ahigh degree of polymerization. The polymerization degree m for theoxyalkylene unit is selected from a range of 10 to 500. If m is lessthan 10, it is difficult to obtain a polyether capable of providing arubber-like cured product having sufficient elongation or a polyetherhaving a viscosity suitable for a practical processability level. On theother hand, if m is greater than 500, the heat resistance and theweather resistance of the elastomer obtained from the room temperaturecurable composition of this invention are poor.

As divalent hydrocarbon group R², there can be mentioned, for example,methylene group, ethylene group, trimethylene group, tetramethylenegroup, phenylene group, cyclohexylene group and the group represented by##STR5## Among them, methylene group is preferred in view of the easyavailability of the raw material.

It is necessary that X is an aromatic or heterocyclic ring for purposesof heat resistance and weather resistance. For the same reason, sulfuratoms in the --S--X--S--bond are preferably bonded to carbon atomsconstituting X.

The monovalent hydrocarbon group R⁴ can be selected from alkyl group,alkenyl group, aryl group, aralkyl group, etc. Methyl group, ethylgroup, propyl group, butyl group, pentyl group, hexyl group, cyclohexylgroup, vinyl group, allyl group, phenyl group and β-phenylethyl groupare preferable in view of the ease of synthesis and availability of theraw material. Among them, methyl group is particularly preferred.

As R⁶ and R⁷, the divalent hydrocarbon groups of R² can be exemplified.R⁶ is preferably methylene group in view of the availability of the rawmaterial. R⁷ is preferably ethylene group, trimethylene group ortetramethylene group, and trimethylene group is particularly preferredin view of the ease of synthesis and availability of the raw material.The alkyl group R⁸ with 1 to 6 carbon atoms is preferably methyl groupor ethyl group, particularly, methyl group since the hydrolyzability ofthe alkoxy group represented by R⁸ O-bonded to the silicon atom is high.The number a for the hydrolyzable groups is selected from the range of 1to 3 and a is preferably 2 in order to obtain a rubber-like curedproduct with high elongation.

The polyether of this invention can be synthesized, for example, byreacting the epoxy groups in component (a) and (c) described above withthe mercapto groups in component (b). Typical examples of component (A)include those prepared by condensing a polyoxyethylene orpolyoxypropylene end-blocked with hydroxyl groups with epichlorohydrinin the presence of a basic catalyst. As component (B),2,5-dimercapto-1,3,4-thiadiazole, dimercapto benzene, dimercaptotoluene, dimercapto xylene and dimercapto naphthalene are recommended,because of the availability of the raw material, ease of the reactivitywith epoxy groups, good yield and balance of the physical property ofthe polyether, etc. Among them, 2,5-dimercapto-1,3,4-thiadiazole isparticularly preferred in view of the reason described above. Specificexamples of component (C) are, β-glycidoxyethyltrimethoxysilane,γ-glycidoxypropyltrimethoxysilane, β-glycidoxyethyltriethoxysilane,γ-glycidoxypropyltriethoxysilane, methyl(β-glycidoxyethl)dimethoxysilane, methyl(γ-glycidoxypropyl)dimethoxysilane, methyl(β-glycidoxyethyl)diethoxysilane, methyl(γ-glycidoxypropyl)diethoxysilane, phenyl(β-glycidoxyethyl)dimethoxysilane, phenyl(γ-glycidoxypropyl)dimethoxysilane, dimethyl(β-glycidoxyethyl)methoxysilane, and dimethyl(γ-glycidoxypropyl)methoxysilane.

The reaction of components (A), (B) and (C) is preferably carried out ata temperature higher than the ambient temperature, for example, underthe condition from 50° to 150° C. In this case, it is preferred to usesuch a compound as methanol, ethanol, phenol, salicylic acid, tris(dimethyl aminomethyl)phenol, benzyl methylamine, tributyl amine or2-methyl imidazole as a reaction promotor. Methanol is a preferredexample. Although the reaction can be carried out without solvent,hydrocarbon, ether, ester or other type solvent may be used.

The blending ratio of components (A), (B) and (C) is theoretically (A) :(B): (C)=p: (P+1) : 2 on a molar basis. However, components (B) and (C)may be used in a slight excess over the theoretical amount.

Components (A), (B) and (C) may be added simultaneously for reaction,but it is preferred to conduct the chain extension first by reactingcomponent (A) with component (B). As stated before, the amount ofcomponent (B) is added in slight excess to component (A) on a molarbasis to obtain the polyether within the desired molecular weight range.Then, the required or slightly excessive amount of component (C) isadded and reacted. By this procedure the polymerization degree is easilycontrolled and the hydrolyzable groups can surely be introduced to theends of the molecular chain.

Further, n is a number of 1 or greater and it should be selected so asto provide a molecular weight of the polyether of from 1000 to 50,000.When the polyether of this invention is used as a base polymer for asealant, and the molecular weight is lower than 1000, then theelongation of the cured elastomer is insufficient as a sealant. While onthe other hand, if the molecular weight is greater than 50,000, theviscosity of the base polymer is too high for good workability.

The ingredient (II) in the composition of this invention is to give thecomposition an appropriate non-flowing property and reinforcingproperty. The ingredient (II) may be exemplified by fumed silica,precipitated silica, pulverized silica, diatomaceous earth, calciumcarbonate, titanium oxide, alumina, aluminum hydroxide, iron oxide, talcand clay. The inorganic fillers may have a surface treatment of organicsilicon compounds, for example, trimethylchlorosilane,hexamethyldisilazane, hexamethylcyclotrisiloxane,octamethylcyclotetrasiloxane or silicone oil. The amount of ingredient(II) used is within a range from 3 to 300 parts by weight and,preferably, from 5 to 200 parts by weight based on 100 parts by weightof ingredient (I). If the amount of ingredient (II) is less than 3 partsby weight, neither non-flowing property nor reinforcing property can beobtained. On the other hand, if it is greater than 300 parts by weight,the viscosity of the composition is increased to lower the workability.

The curing catalysts, as ingredient (III), used in this invention may beexemplified by tin carboxylates such as tin octylate; organo tincarboxylates such as dibutyl tin dilaurate, dibutyl tin dimaleate anddibutyl tin phthalate; organo tin oxides and reaction products thereofwith esters; organic titanate such as tetrabutyl titanate; amines; aminesalts; quarternary ammonium salts; guanidine derivatives, etc. Thecuring catalyst is preferably used within a range from 0.001 to 20 partsby weight based on 100 parts by weight of ingredient (I). If the amountof ingredient (III) is below the above specified range, the curing rateis too slow making the curing composition not suitable for use. While onthe other hand, an excessive amount has no accelerating effect andresults in the risk of bleeding or deposition.

Since the composition of this invention is self-adhering, there is norequirement for using silane coupling agents ordinarily employed forproviding adhesion. It is, however, possible to use such agents forenhancing the bonding property, or to add hydrolyzable silanes to thecomposition with an aim or prolonging shelf-life of one packagecontainers. The hydrolyzable silanes may be exemplified by ##STR6##

Polymers obtained by partial hydrolysis and condensation of thesesilanes may also be used. Good shelflife in one package containers mayalso be obtained by addition of monovalent primary alcohols such asmethanol or ethanol.

Further, it is possible to add agents which give the compositionthixotropy such as hydrogenated castor oil or to add a plasticizer suchas dioctylphthalate, butylbenzyl phthalate and chlorinated paraffin.

The composition of this invention can be used as a onepackage type asdescribed above, as well as a two-package type in which a portioncomprising the ingredients (I) and (II), and a portion comprising theingredient (III) are stored separately and mixed before use.

The composition of this invention has an adhesive property beforecuring, and the elastomer obtained after curing is excellent in heatresistance and weather resistance. Further the cured elastomer has noresidual surface tackiness, and no soiling occurs due to the depositionof dust. Thus the composition is suitable for use as a sealant requiringweather resistance such as for joints of building outer walls, orrequiring heat resistance such as joining parts of transportationmachines, etc. exposed to relatively high temperature.

EXAMPLES OF THE INVENTION

This invention will now be described more specifically by way ofexamples, in which all parts are parts by weight and "%" means "% byweight".

EXAMPLE 1

To 5 moles (10 epoxy gram equivalent) of polyoxypropylene end-blockedwith glycidyl groups having an average polymerization degree of 15,molecular weight of about 1000 and viscosity at 25° C. of 270 cSt, wereadded 6 moles of 2,5-dimercapto-1,3,4-thiadiazole represented by:##STR7## and methanol in an amount of 10% to the polyoxypropylene. Thereaction was started by stirring and heating at 60° C. in a nitrogenatmosphere. The reactor content was sampled at 4 hour intervals forconducting NMR observation of the proton peak of epoxide methylene (2.67ppm based on tetramethyl silane) and for measurement of the viscosity at25° C. After 12 hours from the start of heating under stirring, theproton peak of the epoxide methylene disappeared and the viscosity whichhad been 100 cSt at start reached 1,800 cSt. Subsequently 2.2 moles of##STR8## were added and heating with stirring was continued under thesame conditions. The reaction mixture was again sampled at 4 hourintervals after adding the silane. The mercapto group was determined byadding iodine for reaction with the mercapto group and conducting backtitration for the remaining iodine with sodium thiosulfate. The mercaptogroup was no longer detected 12 hours after the addition of silane. As aresult, the reaction was stopped and methanol was stripped off. Theresultant reaction product was a pale yellow viscous liquid polyetherhaving a viscosity at 25° C. of 19,000 cSt, specific gravity at thattemperature of 1.01 and a number average molecular weight measured byGPC of 6,500. This polyether, P-1, is end-blocked with hydrolyzablesilyl groups and represented by the following formula.

EXAMPLE 2

To 5 moles (10 epoxy gram equivalent) of polyoxypropylene end-blockedwith glycidyl groups having an average polymerization degree of 32,molecular weight of about 2000 and viscosity at 25° C. of 550 cSt, wereadded 6 moles of 2,5-dimercapto-1,3,4-thiadiazole and ethanol in anamount of 10% to the polyoxypropylene. The reaction was started bystirring and heating at 60° C. in a nitrogen atmosphere. The reactorcontent was sampled at 4 hour intervals for conducting NMR observationof the proton peak of epoxide methylene and for measurement of theviscosity at 25° C. After 12 hours from the start of heating understirring, the proton peak of the epoxide methylene disappeared and theviscosity which had been 270 cSt at start reached 4,400 cSt.Subsequently 2.2 moles of ##STR9## were added and heating with stirringwas continued under the same conditions. The reaction mixture was againsampled at 4 hour intervals after adding the silane. The mercapto groupwas determined by the same method as in Example 1. Since the mercaptogroup was no longer detected 12 hours after the addition of silane, thereaction was stopped and ethanol was stripped off. The product was apale yellow viscous liquid polyether having a viscosity at 25° C. of29,000 cSt, specific gravity at that temperature of 1.01 and a numberaverage molecular weight measured by GPC of 11,000. This polyether, P-2,is end-blocked with hydrolyzable silyl groups and represented by thefollowing formula. ##STR10##

EXAMPLE 3

To 3 moles (6 epoxy gram equivalent) of polyoxypropylene end-blockedwith glycidyl groups having an average polymerization degree of 50,molecular weight of about 3000 and viscosity at 25° C. of 970 cSt, wereadded 4 moles of 2,5-demercapto-1,3,4-thiadiazole and methanol in anamount of 10% to the polyoxypropylene. The reaction was started bystirring and heating at 60° C. in a nitrogen atmosphere. The reactorcontent was sampled at 4 hour intervals for conducting NMR observationof the proton peak of epoxide methylene and for measurement of theviscosity at 25° C. After 16 hours from the start of heating understirring, the proton peak of the epoxide methylene disappeared and theviscosity which had been 420 cSt, at start reached 5,400 cSt.Subsequently 2.2 moles of ##STR11## were added and heating with stirringwas continued under the same conditions. The reaction mixture wassampled at 4 hour intervals after adding the silane. The mercapto groupwas determined by the same method as in Example 1. Since the mercaptogroup was no longer detected 16 hours after the addition of silane, thereaction was stopped and methanol was stripped off. The product was apale yellow viscous liquid polyether having a viscosity at 25° C. of26,000 cSt, specific gravity at that temperature of 1.01 and a numberaverage molecular weight measured by GPC of 9,500. This polyether, P-3,is end-blocked with hydrolyzable silyl groups and represented by thefollowing formula. ##STR12##

EXAMPLE 4

To 3 moles (6 epoxy gram equivalent) of the same polyoxypropyleneend-blocked with glycidyl groups having an average polymerization degreeof 50, molecular weight of about 3000 and viscosity at 25° C. of 970 cStas used in Example 3, were added 4 moles of p-dimercaptobenzenerepresented by : ##STR13## and methanol in an amount of 10% to thepolyoxypropylene. The reaction was started by stirring and heating at60° C. in a nitrogen atmosphere. The reactor content was sampled at 4hour intervals for conducting NMR observation of the proton peak ofepoxide methylene and for measurement of the viscosity at 25° C. After12 hours from the start of heating under stirring, the proton peak ofthe epoxide methylene disappeared and the viscosity which had been 400cSt at start reached 5,200 cSt. Subsequently 2.2 moles ofmethyl(γ-glycidoxypropyl) dimethoxysilane were added and heating withstirring was continued under the same conditions. The reaction mixturewas sampled at 4 hour intervals after adding the silane. The mercaptogroup was determined by the same method as in Example 1. Since themercapto group was no longer detected 12 hours after the addition ofsilane, the reaction was stopped and methanol was stripped off. Theproduct was a pale yellow viscous liquid polyether having a viscosity at25° C. of 25,000 cSt, specific gravity at that temperature of 1.01 and anumber average molecular weight measured by GPC of 9,500. Thispolyether, P-4, is end-blocked with hydrolyzable silyl groups andrepresented by the following formula. ##STR14##

EXAMPLE 5

To 3 moles (6 epoxy gram equivalent) of the same polyoxypropyleneend-blocked with glycidyl groups having an average polymerization degreeof 50, molecular weight of about 3000 and viscosity at 25° C. of 970 cStas used in Example 3, were added 4 moles of 1,5-dimercaptonaphthalenerepresented by: ##STR15## and methanol in an amount of 10% to thepolyoxypropylene. The reaction was started by stirring and heating at60° C. in a nitrogen atmosphere. The reactor content was sampled at 4hour intervals for conducting NMR observation of the proton peak ofepoxide methylene and for measurement of the viscosity at 25° C. After12 hours from the start of heating under stirring, the proton peak ofthe epoxide methylene disappeared and the viscosity which had been 430cSt at start reached 5,500 cSt. Subsequently 2.2 moles ofmethyl(γ-grlycidoxypropyl) dimethoxysilane were added and heating withstirring was continued under the same conditions. The reaction mixturewas sampled at 4 hour intervals after adding the silane. The mercaptogroup was determined by the same method as in Example 1. Since themercapto group was no longer detected 12 hours after the addition ofsilane, the reaction was stopped and methanol was stripped off. Theproduct was a pale yellow viscous liquid polyether having a viscosity at25° C. of 27,000 cSt, specific gravity at that temperature of 1.01 and anumber average molecular weight measured by GPC of 9,600. Thispolyether, P-5, is end-blocked with hydrolyzable silyl groups andrepresented by the following formula. ##STR16##

EXAMPLE 6-10

To 100 parts of polyethers (P-1 through P-5) end-blocked withhydrolyzable silyl groups prepared in Examples 1 through 5, were addedfillers, inorganic pigments and thixotropy agents shown in Table 1.After dispersing the ingredients uniformly by a three roll mill, organotin compounds shown in Table 1 were added and mixed with the compositionto give the samples 1 through 5. These samples were cured at roomtemperature for 14 days to form 2 mm thick sheets. The sheets were cutinto the shape of dumbbell No 2 test specimens as defined in JIS K 6301,and hardness and tensile strength were measured. The result wasdesignated as initial state. Then, dumbbell test specimens obtained inthe same manner were placed in a 150° C. oven, and a weatherometer.After subjecting the test specimens to aging conditions (heating or UVirradiation) for periods shown in Table 1, the physical condition of thespecimens was observed and hardness and tensile strength were measured.The results are shown in Table 1.

COMPARATIVE EXAMPLE 1

To 100 parts of polyoxypropylene end-blocked with the group representedby: ##STR17## and having a molecular weight of about 8,000, were addedfillers, inorganic pigments and thixotropy agents shown in Table 1.After dispersing the ingredients uniformly by a three roll mill, organotin compounds shown in Table 1 were added and mixed to give sample 6.Sample 6 was tested in the same manner as described in Examples 6through 10. The results are shown in Table 1.

As can be seen from Table 1, the room temperature curable composition ofthis invention is superior to the composition using the conventionalpolymer described in Comparative Example 1 in terms of both heatresistance and UV resistance (weathering resistance).

EXAMPLES 11-15

Specimens for shear resistance test shown in FIG. 1 were prepared bycuring the samples 1 through 5 prepared in Example 6 through 10 for 28days at room temperature. Shear resistance was measured for these testspecimens by a method similar to that of JIS K 6850. The results areshown in Table 2.

COMPARATIVE EXAMPLE 2

The same test as in Example 11 through 15 was conducted using sample 6prepared in Comparative Example 1. The results are shown in Table 2.

As can be seen from Table 2 the room temperature curable composition ofthis invention has excellent adhesion.

                                      TABLE 1                                     __________________________________________________________________________                                                            Comparative                                Example 6                                                                            Example 7                                                                            Example 8                                                                            Example 9                                                                            Example                                                                              Example 1             Sample No.           Sample 1                                                                             Sample 2                                                                             Sample 3                                                                             Sample 4                                                                             Sample                                                                               Sample 6              Polyether No.        P-1    P-2    P-3    P-4    P-5    --                    __________________________________________________________________________    Filler                                                                              Colloidal calcium carbonate                                                                  50     50     50     50     50     50                    (parts)                                                                             treated with fatty acid                                                       Light calcium carbonate treated                                                              20     --     20     20     20     20                          with fatty acid                                                               Heavy caldium carbonate                                                                      30     50     30     30     30     30                    Pigment                                                                             Titanium oxide 10     10     10     10     10     10                    (parts)                                                                             Carbon black   0.25   0.25   0.25   0.25   0.25   0.25                  Thixotropy agent (parts)                                                                           2      2      2      2      2      2                     Hydrogenated castor oil                                                       Organo tin                                                                          Dibutyl tin oxide                                                                            1      --     1      1      1      1                     compound                                                                            Dibutyl tin dilaurate                                                                        --     1      --     --     --     --                    (parts)                                                                       Initial                                                                             Hardness       16     24     18     16     17     16                    state Tensile strength (kgf/cm.sup.2)                                                              14     21     16     15     14     16                          Elongation (%) 600    350    710    790    760    630                   150° C.                                                                      Aged state     no     no     no     no     no     notably               heating              abnormality                                                                          abnormality                                                                          abnormality                                                                          abnormality                                                                          abnormality                                                                          brittle due           after                                                   to depolymer- -7                                                              days       ization                                                            1                           Hardness       14     22     16     20     19     impossible                  Tensile strength (kgf/cm.sup.2)                                                              16     18     19     18     16     to measure                  Elongation (%) 630    420    760    630    620                          UV ray                                                                              Aged state     no     no     no     no     no     cracking              irradiation          abnormality                                                                          abnormality                                                                          abnormality                                                                          abnormality                                                                          abnormality                                                                          resulted              after Hardness       17     25     19     18     19     6                     3,000 Tensile strength (kgf/cm.sup.2)                                                              19     23     20     16     15     3                     hours Elongation (%) 580    320    700    720    690    170                   __________________________________________________________________________

                                      TABLE 2                                     __________________________________________________________________________                                                     Comparative                                     Example 11                                                                          Example 12                                                                          Example 13                                                                          Example 14                                                                          Example 15                                                                          Example 2                    Sample No.         Sample 1                                                                            Sample 2                                                                            Sample 3                                                                            Sample 4                                                                            Sample 5                                                                            Sample                       __________________________________________________________________________                                                     6                            Glass Shear resistance (kgf/cm.sup.2)                                                            9     12    10    8     9     3                                  Cohesive failure rate (%)                                                                  100   100   100   100   100   0                            Aluminum                                                                            Shear resistance (kgf/cm.sup.2)                                                            8     14    9     10    11    3                                  Cohesive failure rate (%)                                                                  100   100   100   100   100   0                            Polyvinyl                                                                           Shear resistance (kgf/cm.sup.2)                                                            11    12    11    9     10    2                            chloride-                                                                           Cohesive failure rate (%)                                                                  100   100   100   100   100   0                            coated                                                                        steel plate                                                                   __________________________________________________________________________

What is claimed is:
 1. A polyether having a number average molecularweight from 1000 to 50,000, end-blocked with hydrolyzable silyl groupsand represented by the general formula: ##STR18## where R¹, R², R⁶ andR⁷ individually represent a divalent hydrocarbon group, R⁴ represents amonovalent hydrocarbon group, R⁸ represents an alkyl group with 1 to 6carbon atoms, X represents an aromatic or heterocyclic ring, arepresents a number from 1 to 3, m represents a number from 10 to 500, nrepresents a number of 1 or greater.
 2. A polyether as defined in claim1, wherein R¹ is a propylene group.
 3. a polyether as defined in claim1, wherein R⁸ is a methyl group or ethyl group.
 4. A polyether asdefined in claim 1, wherein a is
 2. 5. A polyether as defined in claim1, wherein --S--X--S-- is a dehydrogenated residue group of2,5-dimercapto-1,3,4-thiadiazole.
 6. A process for producing a polyetherhaving a number average molecular weight from 1,000 to 50,000,end-blocked with hydrolyzable silyl groups comprising the step ofreacting:(A) a polyoxyalkylene end-blocked with epoxy groups representedby the general formula: ##STR19## where R¹ and R² individually representa divalent hydrocarbon group and m represents a number from 10 to 500,(B) a dimercapto compound represented by the general formula:

    HS--X--SH

where X represents an aromatic or heterocyclic ring, and (C) an organosilicon compound having an epoxy group and hydrolyzable groupsrepresented by the general formula: ##STR20## where R⁴ represents amonovalent hydrocarbon group, R⁶ and R⁷ individually represent adivalent hydrocarbon group, R⁸ represents an alkyl group with 1 to 6carbon atoms and a represents a number from 1 to
 3. 7. A process asdefined in claim 6, wherein the component (B) is an aromatic compound orheterocyclic compound in which two mercapto groups are bonded to carbonatoms constituting an aromatic ring or heterocyclic ring. --
 8. Aprocess as defined in claim 6, wherein the component (B) is heterocycliccompound or an aromatic compound selected from2,5-dimercapto-1,3,4-thiadiazole, dimercaptobenzene, dimercaptotoluene,dimercaptoxylene or dimercaptonapthalene.
 9. A process as defined inclaim 6 wherein the components (A), (B) and (C) are reacted at atemperature higher than the ambient temperature.
 10. A productionprocess as defined in claim 6, wherein components (B) and (C) are in astoichiometric excess.
 11. A process as defined in claim 6, whereincomponent (A) is first reacted with component (B), and the reactionproduct of component (A) and component (B) is then reacted withcomponent (C).